Boom locking apparatus



BOOM LUCIING MPARATUS Filed Oct. 9. 1962 3 Sheets-Sheet l www ff F/SMMMM w m mir/EMM. M ff www MAQ/M Nov. 16, 1965 .1. P. wAlTE BOOM LOCKING APPARATUS Filed OL. 9

I5 Sheets-Sheet 2 M mfr mn@ A. S ...Wf s U Nr wm J j Y. B

ffoRNEYs Nov. 16, 1965 J. P. wAlTE BOOM LOCKING APPARATUS Filed ooi. 9, 1962 5 Sheets-Sheet. 5

INVENTOR. JOHN P. WA/TE gig'.

)Vndrus Sta/K9 Arron/sys United States Patent Oli-ice 3,217,910 Patented Nov. 16, 1965 3,217,910 BOOM LOCKING APPARATUS John P. Waite, Menomonee Falls, Wis., assignor to J. P. Waite, Inc., Milwaukee, Wis., a corporation of Wisconsin Filed Oct. 9, 1962, Ser. No. 229,420 2 Claims. (Cl. 214-138) This invention relates to a power operated construction apparatus, such as a back hoe or the like, and more particularly to a device for locking a boom in position with respect to the supporting structure.

The conventional back hoe includes a boom which is pivotally connected to the deck or supporting structure -of the hoe, and the outer end of the boom supports a dipper stick which carries a dipper. If during digging, the dipper encounters a hard material which is diicult to penetrate, the boom with pivot upwardly rather than the dipper digging into the material, because the combined weight of the dipper and boom is not sucient to cause penetration of the hard material.

The present invention is directed to a mechanical device associated with the boom for bringing the entire weight of the cab and supporting structure to bear on the dipper to increase the force of penetration of the dipper into the material to be excavated.

According to one form of the invention, the boom is pivotally connected to the deck or supporting structure by pins, and one of the pins carries a gear which is freely rotatable on the pin. A locking arm is attached to the gear and extends over the boom. When engaged with the boom and locked, the arm prevents upward movement of the boom with respect to the deck or supporting member.

The freely rotatable gear is engaged with a second gear mounted on a shaft journalled on the deck. A brake is associated with the shaft and by engaging the brake, the gears are prevented from rotating.

In operation of the back hoe, the brake is normally engaged, and as the boom is lowered, the gears will not rotate nor will the locking arm be moved. However, if it is desired to lock the boom in a lowered position with respect to the cab, the brake is released and the arm will fall by gravity until it engages the upper surface of the boom. At this time, the brake is re-engaged causing the arm to be secured against movement. This prevents the boom from being moved upwardly and in effect locks the boom to the cab so that the entire weight of the supporting structure will bear downwardly during digging.

In another form of the invention, meshing gears are mounted on the boom and supporting structure, respectively, and a brake is associated with one of the gears. As the boom is pivoted with the brake released, the gears travel relative to each other. When it is desired to lock the boom to the supporting structure, the brake is engaged which locks the gears against movement and thereby locks the boom.

In a third form of the invention, telescopic or extendible members are connected to the boom and mast, respectively, and a braking or locking mechanism is ernployed to prevent relative movement between the telescopic members and thereby lock the boom to the supporting structure.

The present invention presents a simple and inexpensive means of bringing the weight of the supporting structure to bear on the boom to increase the force exerted during digging. The apparatus can be readily adapted to conventional back hoes or cranes or other equipment using a pivoting boom without any major alterations of the parts or elements of the boom or supporting structure.

The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a side elevation of a back hoe employing the boom locking `device of the invention;

FIG. 2 is a fragmentary plan view showing the attachment of the boom to the deck;

FIG. 3 is a vertical section taken along line 3 3 of FIG. 2;

i FIG. 4 is a fragmentary plan view of a modified form of the invention showing the attachment of the boom to the deck;

FIG. S is a view taken along line 5-5 of FIG. 4;

FIG. 6 is a fragmentary side elevation of a second modied form of the invention;

FIG. 7 is a section taken along line 7-7 of FIG. 6;

FIG. 8 is a section taken along line 8 8 of FIG. 6;

FIG. 9 is a fragmentary side elevation of a third modiied form of the invention;

FIG. l0 is a plan view of the structure of FIG. 9;

FIG. 11 is a fragmentary side elevation of a fourth modified form of the invention; and

FIG. 12 is a plan view of the structure of FIG. 11.

The drawings illustrate a power operated back hoe having a cab 1 which houses the drive mechanism and is movable on endless crawlers or treads 2.

A boom 3 is pivotally connected by pins 4 to lugs 5 which extend outwardly from the deck 6 of the cab. A dipper stick 7 is pivotally secured to the outer end of the boom 3 and the dipper stick carries a dipper 8 which is adapted to penetrate and dig into the material to be excavated.

The dipper 8 and the dipper stick 7 are pivoted about the boom by a cable 9 which is secured to a cable drum 10 supported on deck 6. Cable 9 passes over one of a pair of sheaves 11, which are secured to boom 3, and over sheave 12 which is secured to the forward edge of the dipper. The cable 9 returns over the other of the sheaves 11 and is dead ended on the boom, as indicated by 13. With this sheaving arrangment the dipper is drawn inwardly toward the boom as cable 9` is retrieved and moved away from the boom as the cable 9 is let out.

The boom 3 is raised and lowered with respect to the deck 6 by a conventional sheaving arrangement in which a cable 14, which is secured to cable drum 15, passes over sheaves 16 and 17 and is dead ended on arms 18, which are pivotally attached to the upper end of dipper stick 7 and supports the sheave 17. Sheave 16 is rotatably secured to mast 19 which extends upwardly from the deck 6 of cab 1. By retrieving cable 14, sheave 17 is moved toward sheave 16 thereby pivoting boom 3 upwardly about the forward portion of the cab, while letting out cable 14 serves to pivot the boom 3 downwardly with respect to the cab 1.

During the digging operation, the dipper 8 may frequently encounter hard materials which are diicult to penetrate and the boom may tend to pivot upwardly rather than the dipper digging into the material, because the combined weight of the boom and dipper is not suilcient to cause penetration of the material by the dipper. To overcome this diiculty, a mechanical mechanism is provided to prevent pivotal movement of the boom with respect to the cab 1 or deck 6 so that the entire weight of the cab, the drive unit and the treads 2 will be brought to bear on the dipper to increase the force of penetration. More speciiically, one of the pins 4 carries a gear 20 which is mounted for free rotation on the pin. An arm 21 is secured to the gear 20 by bolts 22 and the outer end of the arm is bent laterally over the upper surface 23 of the boom 3.

The gear 20 meshes with a pinion 24 secured to shaft 3 which is journalled within the lugs 26. The shaft 25 also carries a brake drum 27 which is adapted to be engaged by a brake band 28. The inner surface of the brake band 28 is provided with a suitable brake lining 29 which contacts the outer surface of the drum 27.

As best shown in FIG. 3, the brake is provided with a pair `of spaced ears or pr-ojections 30, one of which is secured to the upper surface of the deck 6 by bolts 31.

The band 28 is urged into engagement with the brake drum 27 by a spring 32 which is positioned around a rod 33.r The rod 33 extends through aligned openings in the ears 30 and the outer end of the rod is provided with a head 34. The spring 32 is interposed between the head 34 and the upper of the ears 30 and serves to urge the ears together and engaged to lock the brake.

The brake mechanism is adapted to be released by a fluid mechanism which includes an air cylinder 35 which is pivotally connected to one of the ears 30. A piston 36 is slidably disposed within the cylinder and the piston rod 37 is pivotally connected to the other of the ears 30. When it is desired to release the braking mechanism, Huid, such as air, is introduced into yone end of the cylinder 35 through line 38, which thereby urges the ears 3) apart and expands the brake band 2S against the force of the spring 32.

The spring 32 normally keeps the brake band 28 in the engaging position so that the pinion 24 and gear 20 are locked against rotation. As the boom 3 is lowered with the brake locked, the arm 21 will not move downwardly with the boom, but will be retained in its original position. If it is desired to lock the boom 3 with respect to the cab 1, the brake is then released by introducing air within the air cylinder which overcomes the force of the spring 32. With the brake released, the arm 21 will then move downwardly by gravity until it engages the upper surface 23 of the boom 3. At this time the brake is re-engaged by cutting off the fiuid pressure in the cylinder and the pinion 24 and gear 20 are thereby secured against rotation. This prevents the boom 3 from moving upwardly and, in effect, locks the boom to the cab so that the entire weight of the cab will bear downwardly during digging.

When it is desired to operate the boom in the normal manner, the brake is released by introducing air into the cylinder 35 and the boom can be then pivoted upwardly. The arm 21 will follow the movement of the boom and when the boom reaches an upward position, the brake ycan then be again locked, which will lock the arm 21 in an upward position where it will not interfere with the normal movement of the boom 3.

FIGS. 4 and 5 illustrate the modified form of the invention. In this embodiment, a shaft 39 is journalled within a bearing 40 secured to the upper surface of the boom 3. A pinion 41 is secured to the shaft and the shaft also carries a brake drum 42.

The pinion 41 engages a gear segment 43 which is secured by bolts 44 to an extension 45 formed on one of the lugs 5. The teeth of the gear segment 43 are on an arc of a circle, the center of which coincides with the axis `of the pin 4 which connects the boom 3 to the lugs 5. With this construction, as the boom 3 is pivoted with respect to the cab 1, the pinion teeth travel along the teeth of the gear segment 43.

To lock the pinion against rotation, a brake band 46 is disposed around the brake drum 42, and a suitable lining 47 is provided on the inner surface of the brake band. The brake band 46 is provided with a pair of spaced ears 48 and a bracket 49 is secured to one of the ears and extends laterally over the boom and is connected to the boom by bolts 50.

As in the case of the first embodiment, the brake band 46 is adapted to normally be locked to the brake drum 42 by means of a spring 51 which is secured around a rod 52. The rod 52 extends through aligned openings in the ears 48 and the spring 51 is interposed between one of the ears and the head 53 of the rod and serves to urge the ears together and lock the brake band to the brake drum.

To release the brake band 46, an air mechanism is employed similar to that disclosed in the first embodiment. A cylinder 54 is connected to one of the ears 46 and a piston 55 is slidable within the cylinder and ycarries a piston rod 56 which is pivotally connected to the other of the ears 48. Air is introduced into one end of the cylinder through line 57 to push the piston rod outwardly and thereby release the brake band against the force of the spring 51.

With the device shown in FIGS. 4 and 5, the brake must be released before the boom 3 can be moved either upwardly or downwardly. For example, if the boom is to be moved downwardly, air is introduced into the cylinder 55 to release the brake and the boom can then be pivoted downwardly with the gear segment 43 serving to drive the pinion 41. With the boom in the lowered position, if it is desired to bring the weight of the entire cab and drive mechanism to bear on the boom, the pressure within the cylinder 55 is released thereby locking the brake and preventing pivotal movement of the boom with respect to the supporting structure.

FIGS. 6 through 8 illustrate a second modified form of the invention in which an extendable or telescopic unit 58 is secured between the boom 3 and the mast 19. According to this embodiment a rod 59 is pivotally connected to lugs 60 secured to the upper surface of the boom 3. The rod is slidable within an outer segmental casing 61 which is formed of two matching halves or segments 62 and 63. A suitable lining material 64 is secured to the inner surface of the segments.

To permit radial movement of the segments 62 and 63, a bolt 65 is threadedly engaged within openings in the upper end of each segment and extends through a slot 66 in the end plate 67. With this construction, the segments 62 and 63 can move radially toward and away from the inner rod 59. The end plate 67 is secured to a bracket 68 which is pivotally connected to the upper portion of the mast.

As the boom 3 is raised and lowered with respect to the supporting structure, the rod 59 moves within the outer casing 61. When it is desired to lock the boom with respect to the supporting structure, a fluid actuating brake mechanism is employed which Will move the outer segments 62 and 63 against the rod 59 and prevent relative movement therebetween. When in the locked position, the boom 3 will be firmly secured to the mast and supporting structure so that the entire weight of the unit can be brought to bear on the dipper.

As best shown in FIG. 7, ears 69 are attached to adjacent ends of the segments 62 and 63, while the opposite adjacent ends of the segments are connected together by pivotal arms 70. One end of a uid cylinder 71 is pivotally connected to one of the ears 69 and a piston 72 is slidable within the cylinder and carries a piston rod 73 which extends outwardly through an opening in the opposite ear. The rod 73 is provided with a head 74 which engages the outer surface of the ear. By introducing air into one end of the cylinder `through line 75 the ears are .brought together to compress the segments 62 and 63 against the rod 59 and thereby lock the segments to the rod.

When it is desired that the boom operate in a normal manner, the pressure within the cylinder is released and the rod can then freely slide within the outer segments so that the boom can be pivoted normally with respect to the supporting structure.

Because of the length of the segments 62 and 63, it is preferred to employ a series of uid cylinders 71. As shown in FIG. 7, two cylinders 71 are used with the supply lines 75 .being connected by line 76 to a common source of fluid pressure.

FIGS. 9 and 10 illustrate a further modified form of the invention and in this embodiment a shaft 77 is journalled Within bearings 78 secured to the upper surface of boom 3. A pinion 79 is secured to the shaft and the shaft also carries a brake drum 80. The pinion 79 engages the teeth of a rack 81 which is slidably mounted within a bracket 82 pivotally connected to one of the bearings 78. The inner end of the rack 81 is pivotally connected to lugs 83 on the supporting structure l.

As the boom 3 is pivoted with respect to the cab 1, the pinion teeth move along the teeth of the rack 81 and the rack 81 will pivot in accordance with pivotal movement of the boom 3.

To lock the pinion 79 and rack 81 against relative movement, a brake mechanism is employed which is identical to that disclosed in FIG. 5. The brake mechanism includes a brake band 84 which is adapted to be secured against the brake drum `80 by a spring 8S. The brake band 84 is released by a fluid mechanism similar to that shown in FIG. 5 including a cylinder 86 which is connected to one of the ears 87 on the brake band and a piston rod 88 is connected to the other. As air is introduced into one end of the cylinder 86 the piston rod 88 is forced outwardly to thereby release the brake band 84 against the force of the spring 85.

FIGS. l1 and 12 illustrate another modified form of the invention in which one end of a rack 89 is pivotally connected to lthe upper surface of the boom 3. The rack is slidable within a housing 90 and the upper end of the housing is pivotally connected to the mast 19.

A shaft 91 carries a pinion 92 having teeth which er1- gage the teeth of the rack 89. -In addition, the shaft 91 carries a brake drum 93. The brake drum 93 is enclosed within a brake band 94 which is secured to the housing 90 by bolts 95.

Pinion 92 is locked with respect to the rack 89 by a brake mechanism identical to that shown in FIG. 5 in which a spring 96 serves to urge the brake band to the closed position While a cylinder 97 is employed to release the brake band in a manner similar to that previously described.

In operating of the apparatus as shown in FIGS. l1 and 12, pivotal movement of the boom will cause relative or telescopic movement between the rack 89 and the housing 90, and the pinion 92 will travel along the teeth of the rack 89 as the boom is pivoted. The boom can be locked at any desired location with respect to the cab 1 by releasing the pressure within cylinder 97 so that the force of the spring 93 will then urge the brake band 94 to the closed position and lock the pinion 92 and rack 89 together.

While the above description has shown a braking mechanism in which a spring is employed to urge the brake band to the braking position and a fiuid cylinder is employed to release the brake band, it is contemplated that these elements may be reversed and the iiuid cylinder may be employed to maintain the brake band in the braking position and the spring may be used to urge the brake band to the non-braking position upon release of the pressure within the cylinder.

Similarly, while the description has shown a spring and a iiuid cylinder for releasing and actuating the brake mechanism, it is contemplated that any desired type of mechanical, hydraulic or electrical equipment can be used in place of the spring and Huid cylinder.

The present invention provides a simple and inexpensive method of bringing the weight of the supporting structure, including the cab, drive mechanism and treads to bear on the boom to increase the force exerted during digging. The apparatus of the invention can be readily adapted to conventional back hoes, cranes or other apparatus employing a boom which is pivotally connected to a supporting structure.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. In a power operated apparatus, a supporting structure, a boom, a shaft pivotally connecting one end of the boom to the supporting structure, iirst gear means mounted for free rotation, second gear means mounted for rotation on the supporting structure and disposed in engagement with said first gear means, holding means connected to said first gear means and including an arm extending over the boom and disposed to engage the boom, and brake means connected to one of said gear means for locking the gear means against relative movement and thereby locking said holding means against the boom to prevent pivotal movement of the boom with respect to the supporting structure.

2. In a power operated apparatus, a supporting structure, a boom, a shaft pivotally connecting one end of the boom to the supporting structure, a gear mounted for free rotation on said shaft, an arm connected to said gear and extending over said boom, a second gear mounted for rotation on the supporting structure and engaged with said iirst gear, brake means associated with said second gear, and means for selectively engaging said brake means to thereby prevent rotation of said gears and lock said arm against the upper surface of the boom to prevent pivotal movement of the boom with respect to the supporting structure.

References Cited by the Examiner UNITED STATES PATENTS 1,503,813 8/1924 Burke 214-138 2,873,871 2/1959 Waite 214-138 3,073,465 1/1963 Strnad 214-140 3,117,686 1/1964 Brown 214--138 HUGO O. SCHULZ, Primary Examiner. 

1. IN A POWER OPERATED APPARATUS, A SUPPORTING STRUCTURE, A BOOM A SHAFT PIVOTALLY CONNECTING ONE END OF THE BOOM TO THE SUPPORTING STRUCTURE, FIRST GEAR MEANS MOUNTED FOR FREE ROTATION, SECOND GEAR MEANS MOUNTED FOR ROTATION ON THE SUPPORTING STRUCTURE AND DISPOSED IN ENGAGEMENT WITH SAID FIRST GEAR MEANS, HOLDING MEANS CONNECTED TO SAID FIRST GEAR MEANS AND INCLUDING AN ARM EXTENDING OVER THE BOOM AND DISPOSED TO ENGAGE THE BOOM, AND BRAKE MEANS CONNECTED TO ONE OF SAID GEAR MEANS FOR LOCKING THE GEAR MEANS AGAINST RELATIVE MOVEMENT AND THEREBY LOCKING SAID HOLDING MEANS AGAINST THE BOOM TO PREVENT PIVOTAL MOVEMENT OF THE BOOM WITH RESPECT TO THE SUPPORTING STRUCTURE. 